Process of making acetic anhydrid.



UNITED STATES PATENT FIcE.

BERNHABD I-IEYMANN, OF ELBERFELD, GERMANY, ASSIGNOR TO FARBEN- FABRIKENOF ELBERFELD 00., OF NEW YORK, N. Y.

PROCESS OF MAKING ACETIC ANHYDRID.

SPECIFICATION forming part of Letters Patent N 0. 683,464, dated October1, 1901.

Application filed December 2'7, 1900. Serial No. 41,261. (No specimens.)

To all whom it may concern.-

Be it known that I, BERNHARD HEYMANN, doctor of philosophy, chemist,(assignor to the FARBENFABRIKEN on ELBERFELD 00., of New York,) residingat Elberfeld, Germany, have invented a new and useful Improvement in theManufacture of Acetic Anhydrid and I hereby declare the following to bea clear and exact description of the invention.

My invention relates to a new and useful process for the production ofacetic anhydrid. This process consists in treating salts of this acid,especially the alkaline salts, with a mixture of chlorin and sulfurousanhydrid,(SO by means of which operation the said salts are transformedinto acetic anhydrid in a very profitable manner.

In carrying out my new process practically I can proceed as follows, theparts being by weight: seventy one parts of gaseous chlorin (two atoms)and sixty-five parts of gaseous sulfurous anhydrid (a little more thanone molecule) are jointly introduced into a closed Vessel containingthree hundred and twentyeight parts of sodium acetate (four molecules)which is free from Water. The vessel is provided with a stirrer. Du ringthis operation it is advisable to cool the vessel in order to keep thetemperature of the mixture at about 20 centigrade. Care may also betaken that sulfurous anhydrid be always present in a slight excess. Thegases introduced are immediately absorbed, acetic anhydrid beingproduced. After the reaction is completed the acetic anhydrid thusprepared is distilled off in vacuo from the resulting mixture. It can befurther purified by a second distillation.

Having now described my invention and in what manner the same is to beperformed, what I claim as new, and desire to secure by Letters Patent,is-= The process for the production of acetic anhydrid which processconsists in treating alkaline salts of acetic acid with a mixture ofchlorin and sulfurous anhydrid and separating the resulting aceticanhydrid from the re action mixture, substantially as hereinbeforedescribed.

nesses.

BERNHARD HEYMANN.

Witnesses: OTTO KONIG,

J. A. RITTERSI-IAUS.

